Reading more and more into the tech stuff of brewing and working on another
batch, I read that using an air difusser and pump can help with a rapid and
very productive fermentation. My questions are as follows :

1. Can I go buy a regular fish tank pump and some tubing with an air-stone ?
2. After the wort has cooled and yeast has been pitched, I insert the air-stone ?
3. how long do I leave the airstone in ? Should I put the lid & airlock on with the
airstone in the fermentor ?

The purpose of pumping air into the wort is to increase the dissolved oxygen content. This allows for healthier yeast cells to develop and flourish in the wort during fermentation. There are several ways to do this and rather than go through them all I recommend you search through the previous entries to this forum then go to www.morebeer.com or www.stpats.com and search these sites for 'aeration'. It is recommended that you place a filter in between the source of oxygen and the stone. Sequence is cool wort, aerate, remove the aeration stone, pitch yeast, then cover. good luck!